1. Field of the Invention
Efficient testing of organic compounds in the modern pharmaceutical laboratory requires the synthesis of large numbers of diverse organic molecules in an automated and high speed manner. The apparatus of the present invention is designed for use in such a system, particularly one which employs solid phase synthesis techniques. It is useful in performing the entire synthesis or for performing only the final cleavage step of radio frequency tagged synthesis.
During the course of the synthesis, various operations must be performed on the samples, including reagent introduction and removal, agitation, washing, and compound removal by cleavage from a resin support. Precise control of temperature, pressure and atmospheric gas mixtures may be required at various stages. These operations are standard and can be performed at task specific work stations which have been designed or modified for use with one or more reactors.
2. Description of the Related Art
Over the last few years, a number of different systems have been developed to produce libraries of large numbers of specific types of organic molecules, such as polynucleotides. However, the usefullness of such systems tends to be limited to the particular type of molecule the system was designed to produce. Our invention is much more general in application. It can be used to synthesize all types of organic compounds including those used in pharmaceutical research, the study of DNA, protein chemistry, immunology, pharmacology or biotechnology.
Aside from the lack of versatility, existing equipment for automated organic synthesis tends to be large and heavy, as well as very expensive to fabricate and operate. Known automated systems also tend to be quite complex, requiring equipment which is limited as to flexibility, speed, and the number and amount of compounds which can as be synthesized. As will become apparent, our system has a simple, elegant design. It is relatively inexpensive to fabricate and operate. However, it is extremely flexible and is capable of producing large numbers and amounts of all types of organic compounds in a high speed, automated manner. It is smaller in size than comparable equipment, permitting more reactors to be used at one time at a work station and it is lighter, thereby facilitating movement of the apparatus between work stations with less effort.
One system of which we are aware was developed for use at Zeneca Pharmaceuticals, Alderley Park, Macclesfield, Cheshire, SK10 4TG, United Kingdom. That system is built around an XP Zymate laboratory robot (Zymark Corporation, Hopkinton, Mass.). The robot arm is situated in the middle of a plurality of stationary work stations arranged in a circle. The arm is programmed to move one or more tube racks from one station to another. However, the Zeneca system has a small throughput capability, as the number of tube racks which can be handled at one time is limited.
An automated peptide synthesizer developed for Chiron Corporation of Emeryville, Calif.., which has similar limitations, is described by Ronald N. Zukermann, Janice M. Kerr, Michael A. Siani and Steven C. Banville in an article which appeared in the International Journal of Peptide and Protein Research, Vol. 40, 1992, pages 497-506 entitled "Design, Construction and Application of a Fully Automated Equimolar Peptide Mixture Synthesizer". See also U.S. Pat. No. 5,240,680 issued Aug. 31, 1993 to Zuckermann and Banville and U.S. Pat. No. 5,252,296 issued Oct. 12, 1993 to Zukermann et al. entitled "Method and Apparatus For Biopolymer Synthesis".
Another approach was developed at Takeda Chemical Industries, Ltd. and is described in an article published in the Journal of Automatic Chemistry, Vol. 11, No. 5 (Sept.-Oct. 1989) pp. 212-220 by Nobuyoshi Hayashi, Tobru Sugawara, Motoaki Shintani and Shinji Kato entitled "Computer-assisted Automatic Synthesis II. Development of a Fully Automated Apparatus for Preparing Substituted N- (carboxyalkyl) Aminio Acids". The Takeda system includes a plurality of stationary units which are computer controlled. The reactor unit includes only two reaction flasks. A plurality of computer controlled solenoid valves regulate the input flow from the reactant supply unit and wash solvent supply unit as well as output to the purification unit, exhaust and drainage unit. Sensors and electrodes feed information back to the computer. That system is complex, costly and inflexible. It is also very limited with respect to the number of compounds which can be synthesized.
A more flexible approach has been suggested by the Parke-Davis Pharmaceutical Research Division of Warner-Lambert, as described by Sheila Hobbs DeWitt et al. in Proc. National Academy of Science, USA, Vol. 90, pp. 6909-6913 August 1993 and in the ISLAR '93 Proceedings. That system employs a Tecan robotic sample processor. A manifold of gas dispersion tubes are employed in combination with glass vials. The glass frits of the tubes contain the solid support during reactions. However, like many prior art systems, in this apparatus, samples from the reaction tubes must be removed from above, using a modified needle as a probe. There is no facility for removal from the bottoms of the tubes. Accordingly, obtaining product from the reactor vessels in the Parke-Davis system is awkward and time consuming.
U.S. Pat. No. 5,472,672 issued Dec. 5, 1995 to Thomas Brennan, entitled "Apparatus and Method for Polymer Synthesis Using Arrays", teaches the use of an automated system in which a transport mechanism is used to move a base having an array of reactor wells in conveyor belt fashion from work station to work station. Sample removal is performed by creating a pressure differential between the ends of the wells. Aside from the difficulties with regard to discharge, this system is complex and lacks flexibility.
We are also aware of system designed by the Ontogen Corporation of Carlsbad, Calif. 92009 as disclosed by John Cargill and Romaine Maiefski in Laboratory Robotics and Automation, Vol. 6 pp. 139-147 in an article entitled "Automated Combinatorial Chemistry on Solid Phase" and disclosed in U.S. Pat. No. 5,609,826 entitled "Methods and Apparatus for the Generation of Chemical Libraries" issued Mar. 11, 1997 to John Cargill and Romaine Maiefski. The system disclosed in the article and patent utilizes a reactor block having an array of reactor vessels. The block is moved along an assembly line of work stations under computer control.
The Ontogen apparatus disclosed in the above mentioned article and patent has a number of shortcomings. It is highly complex and expensive. It does not include any valving structure capable of regulating the fluid discharge from the reactor chambers. Instead, it depends upon pressure differential to cause discharge through s-shaped trap tubes which snap into a fitting on the bottom of each reaction vessel. This takes up a lot of room, preventing the dense packing of the reactor vessels. It also makes product removal awkward.
Because the reactor vessels disclosed in the article and patent cannot be densely packed, mirror image reactors are required in the Ontogen system to discharge into all of the densely packed wells of a standard microtiter plate. As described in U.S. Pat. No. 5,609,826, two different reactor configurations, each capable of receiving a set of 48 reaction vessels, are required to deposit directly into all 96 of the microtiter wells.
Reactor vessels of the type commonly used in the art are not adapted to receive commercially available porus polyethelene microcannisters. As is disclosed in the literature noted below, such microcannisters can be radio frequency transmitter tagged for automated tracking. Hence, it would be very advantageous to have a reactor which could deposit into all the microtiter wells and still utilize reactor vessels capable of receiving commercially available microcannisters.
International Publication Number WO 97/10896 under the Patent Cooperation Treaty published on Mar. 27, 1997 teaches apparatus for simultaneous solid phase chemical synthesis developed by Berlex Laboratories, Inc. of Richmond, Calif. The Berlex equipment utilizes a manifold valve block including a plurality of aligned valve inserts which are controlled by valve stems. The stems are rotated by hydraulic cylinders positioned on either side of the manifold. The Berlex apparatus accomodates 96 reactor vessels at one time in a densely packed array. However, the reactor vessels cannot receive porous microcannisters with radio frequency tags. Moreover, this reactor requires a specially designed solvent delivery system.
Personnel at Bristol-Myers Squibb Company of Princeton, N.J. 08543 developed an earlier version of the present apparatus designed for use in the simultaneous synthesis of diverse organic compounds. Like the present invention, it consisted of stackable modules which are moveable among nesting sites located on work station platforms. The reactor module in that version includes a heat transfer block adapted to receive an array of reactor vessels. The reactor vessels are in the form of solid phase extraction cartridges without sorbent. Each has a bottom outlet port. A plurality of separate valves arranged in rows are located below the vessels. The valves consist of stopcocks which are gang-controlled to regulate the discharge from the reactor vessel outlet ports into aligned channels, each formed by a pair of threated Leur tip adapters. The reactor module is situated over a discharge module. The inlet openings in the discharge module are adapted to accept the threaded ends of the Leur tip adapters. The discharge module consists of a multi-well collector block or a drain block. A solvent introduction module, which includes a pressure plate having an array of openings and a septum, is received over the reactor module. The downwardly projecting rim defining each pressure plate opening cooperates with the septum to engaged the mouth of the aligned reactor vessel to maintain a fluid tight seal.
Although that apparatus was a vast improvement over the prior art systems, it still had some disadvantages. For example, the apparatus was still relatively large and has connectors and levers extending outwardly from the sides, allowing only two reactors to fit under a standard fume hood at one time. Each reactor weighed about 18 pounds and was costly to fabricate. Thus, improvement in the areas of size, weight and cost are possible. A more elegant valve system, with fewer moving parts, is also desireable. Provision for receiving commercially available porous microcannisters with radio frequency transmitter tags for automated encoding in the reactor vessels would be extremely advantagous. Moreover, a structure which could accommodate standard microtiter plates or blocks for specimen collection would be an important advance. Improvements in these areas are embodied in the present invention.
Our approach to the automation problem in this invention is to employ modules of simplified design and construction which can be readily arranged in sets to perform the required operations and which are light in weight so as to be easily moveable among nest sites at standard work stations. This permits the greatest amount of flexibility at the least cost. Due to more compact design, more reactors can be assembled and employed at one time by creating multiple nest sites at a single work station, such as an orbital shaker. For time consuming operations, several work stations can be in use simultaneously, to permit parallel flow of reactors and therefore eliminate bottlenecks. For less time consuming operations, fewer work stations can be used, as long as the flow of reactors is not impeded. Because the reactors are lighter in weight, they are easier to transport. Accordingly, maximum throughput is acheived with minimum investment.
In addition, the apparatus of the present invention is designed to permit sample removal from the bottom of the reactor vessels as in the earlier version of the Bristol-Myers Squibb equipment. However, unlike the earlier equipment system, the present invention employes simplified valving in the form of a unique pinch valve block located beneath the reactor block. The valve block includes plates with sets of aligned, relatively moveable ribs. Each rib set is aligned with the outlet tubes associated with a different row of reactor vessels. Movement of the rib surfaces causes force to be applied to the outlet tubes through Telfon encapsulated silicone O-ring cord sections situated between one rib surface and the adjacent outlet tubes, such that the tubes are simultaneously closed (pinched) without crushing or damaging the tube walls. As a result, the tube walls will reliably resume their original open condition each time the force is released.
The apparatus of the present invention includes a reactor block, located above the valve block, which accepts an array of reactor vessels. The vessels may be any plastic or glass tube with a bottom port, such as a standard solid phase extraction cartidge without sorbent. However, the reactor vessels are preferrably designed to receive porus polyethelene microcannisters provided with radio frequency transmitter tags for automated tracking. The apparatus can be used for the entire synthesis or only the final cleavage step in radio frequency tagged synthesis, as desired.
The reactor module is adapted to mount over a discharge module. The discharge module may consist of a collection block with an array of wells for collection tubes or vessels. Preferrably, it takes the form of a 96 well microtiter block of standard size and dimension. If the reactor vessels are large enough to accept commercially available porus microcannisters, they may be too large to permit them to be packed tightly enough to discharge into all of the 96 wells of a standard microtiter block at once. A funnelling device could be interposed between the valve block and the microtiter plate to direct the discharge from the reactor vessels into the wells of the plate. However, such a device is bulky and expensive to fabricate. Alternatively, as in the Ontogen system mentioned above and disclosed in U.S. Pat. No. 5,609,826, mirror image reactors (referred to as type "A" and type "B") could employed, each capable of holding 48 reactor vessels and discharging into a different set of 48 wells in the 96 well microtiter plate.
Our system overcomes the costs and problems of requiring an interposed funnelling device or having two reactor configurations by employing a single reactor block with 52 possible reactor vessel positions, instead of the conventional 48. Either one of two different sets (referred to as "odd" or "even") of 48 positions out of the possible 52 positions can be selected for use. By shifting the position of the reactor block relative to the microtiter plate, discharge into either the odd or even well set in the microtiter plate can be achieved.
Internal vertical supports are employed to facilitate alignment of the blocks as the reactor module sets are formed. The supports each have a plurality of different levels. Different blocks are designed to rest on different levels. In this way, different reactor configurations are easily formed. For example, reactors with or without temperature control blocks can be assembled. Simple nesting brackets with chamfered surfaces make installation of the reactors on the work stations a quick and easy task.
Since the modifications to standard work stations to accept the reactors of the present invention are simple and inexpensive to make, little time or cost is involved in converting a conventional laboratory for use with the system of present invention. This dramatically increases the speed of the set up of a facility to perform the synthesis process, as customized work stations, specialized computers and complex interfaces are not required.
It is, therefore, a prime object of the present invention to provide apparatus for the synthesis of multiple organic compounds which is mechanically simple, small in size, light in weight, relatively inexpensive to construct, does not require extensive set up time, is extremely flexible and has high throughput.
It is another object of the present invention to provide apparatus for the synthesis of multiple organic compounds which consists of a plurality of stackable modules adapted to be moved as a unit among nest sites on work station platforms.
It is another object of the present invention to provide apparatus for the synthesis of multiple organic compounds which can be used for performing the entire synthesis or only the final cleavage step of radio frequency tagged synthesis.
It is another object of the present invention to provide apparatus for the synthesis of multiple organic compounds which includes a multiple valve block in which sets of aligned ribs of relatively moveable plates act through Teflon encapsulated silicone O-ring cord sections to close rows of outlet tubes to regulate the discharge from the reactor vessel ports.
It is another object of the present invention to provide apparatus for the synthesis of multiple organic compounds which is compatable for use with a standard 96 well microtiter collection plate where a single configuration reactor block with 52 reactor vessel positions can be employed to discharge into either the even or the "odd" 48 well sets of the plate by shifting the relative position of the microtiter plate.
It is another object of the present invention to provide apparatus for the synthesis of multiple organic compounds which utilizes reactor vessels adapted to receive porus microcannisters with radio frequency transmitter tags.
In accordance with one aspect of the present invention, apparatus useful for the synthesis of multiple organic compounds is provided. The apparatus is adapted to receive an array of individual reactor vessels. Each vessel has a port connected to an outlet tube. Valve means simultaneously regulate the discharge from the vessels through the outlet tubes. The valve means includes first and second relatively moveable surfaces between which the outlet tubes extend. Resilient means are interposed between one of the surfaces and the outlet tubes. Relative movement of the surfaces causes force to be applied through the resilient means to close the outlet tubes.